Water and the Fitness of the Environment



Key words




Adhesion- The attraction between different kinds of molecules

aqueous solution
- A solution in which water is the solvent.

buffer- A substance that consists of acid and base in a solution and that minimizes changes
in pH when extraneous acids or bases are added to the solution

cohesion-
The binding together of like molecules, often by hydrogen bonds.

evaporative cooling-
The property of a liquid whereby the surface becomes cooler during evaporation,
owing to a loss of highly kinetic molecules to the gaseous state.

heat of vaporization-
The quantity of heat a liquid must absorb for 1 gram of it to be converted from the liquid to the gaseous state.

heat-
The total amount of kinetic energy due to molecular motion in a body of matter. Heat is energy in its most random form.

hydration shell-
The sphere of water molecules around each dissolved ion.

hydrogen ion-
A single proton with a charge of +1. The dissociation of a water molecule (H2O) leads to the generation of a hydroxide ion (OH-) and a hydrogen ion (H+).

Joule(J)- A unit of energy

Kinetic energy-
the energy of motion

Molarity- measure of concentration. Moles / Liters

Mole(mol)-
The number (mol) of grams of a substance that equals its molecular weight

Polar molecule- opposite ends of the molecules have opposite charges

pH- a measure iod the concentration of hydrogen ions

Solute-
A substance that is dissolved in a solution.

Solvent-
the substance that dissolves the solute

Solution-
A homogeneous, liquid mixture of two or more substances.

Specific heat- amount of heat necessary for one gram of a substance to change its temperature by one degree Celsius

Surface tension-
A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules.
http://thephotoforum.com/gallery/files/96-junephoto45-SurfaceTension.jpg
http://thephotoforum.com/gallery/files/96-junephoto45-SurfaceTension.jpg

temperature- the average kinetic energy
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The image “http://www.lbl.gov/Science-Articles/Archive/sabl/2005/February/assets/water_molecules.jpg” cannot be displayed, because it contains errors.


Chapter Summery


The polarity of water molecules results in hydrogen bonding

http://upload.wikimedia.org/wikipedia/en/thumb/0/07/Water_molecule.svg/350px-Water_molecule.svg.png
http://upload.wikimedia.org/wikipedia/en/thumb/0/07/Water_molecule.svg/350px-Water_molecule.svg.png
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The image “http://www.lbl.gov/images/MicroWorlds/H2OH-bond.gif” cannot be displayed, because it contains errors.


Attraction of Water
• Attraction between polar molecules
• Attraction is electric
• Slightly positive hydrogen is attracted to the slightly negative oxygen

Four things Water contributes to Earth
• Water’s cohesive behavior
• Ability to stabilize temperature
• Expansion upon freezing
• Versatility as a solvent

Water stabilizes air temperature by absorbing heat from air that is warmer and releasing the stored heat to the air is cooler

Example: An ice cube cools a drink not by adding coldness to the liquid, but by absorbing heat as the ice cube melts

Water freezes at 0 degrees Celsius and boils at 100 degrees Celsius.